1. Field of the Invention
This invention relates generally to noise attenuation, and is concerned in particular with an improved device for adjustably mounting noise attenuating ear cups on the helmet shells worn by military personnel and workers in various industrial environments.
2. Description of the Prior Art
Noisy environments such as those found in tanks, helicopters, and other military vehicles present a need to protect the occupants"" hearing during prolonged exposure, without impairing clear radio/intercom communication, and while maximizing both wearer comfort and the surface area protected by the helmet.
Prior art approaches typically rely on large cutouts in the sides of the helmet protective shell to accommodate protruding ear cups. Clamping springs and/or chin straps are used to apply sufficient inward force to achieve an effective sonic seal around the ears. This approach has a number of limitations. For example, the cutouts in the sides of the helmet shell reduce the protected area. The forces applied by the clamping springs are not readily adjustable, and thus comfort cannot be maximized by minimizing clamping forces as conditions warrant. Also, chin straps restrict jaw movement, have limited clamping ability, and can chafe the skin with prolonged use.
Another prior art approach combines low profile ear cups mounted on a clamping spring band that loops over the top of the wearer""s head. Once the ear cups are in place, the protective helmet with its crown padding removed, is donned over the spring band.
While this approach does not require large cutouts in the helmet shell, it too has other drawbacks. More particularly, the clamping forces applied by the spring bands are not readily adjustable for comfort and effective sonic sealing. Also, handling the separate helmet and ear cup/headband assembly is inconvenient. Chin straps are still necessary in order to stabilize the helmet shell.
For commercial applications that do not require military-type protection, the protective shell typically does not encroach below the top of the wearer""s ears. Here, long spring levers with attached ear cups protrude from mounting points on the shell down past its brim to ear level. While this approach does not require a chin strap to stabilize the helmet, clamping forces are again not readily adjustable for comfort and effective sonic sealing. Moreover, the spring levers are prominent, delicate and vulnerable to damage during normal use.
The overall objective of the present invention is to provide an improved device for mounting noise attenuating ear cups to helmet shells in a manner that supports clear radio/intercom communication while maximizing wearer comfort and without reducing the surface area protected by the helmet.
Devices in accordance with the present invention includes clamp plates secured to the helmet shell in operative positions extending along side edges of the shell. Flexible straps extends along inner surfaces of the clamp plates. The straps have first ends anchored to the clamp plates, intermediate portions bulging inwardly from the clamp plates, and opposite second ends constrained for longitudinal movement relative to the clamp plates. The ear cups are attached to and supported exclusively by the intermediate strap portions. By longitudinally adjusting the second strap ends, the extent to which the intermediate strap portions bulge inwardly can be adjusted to thereby effect a corresponding adjustment of the inward forces being applied to the ear cups against the wearer""s head.
Other features and advantages of the present invention will now be described in greater detail with reference to the accompanying drawings, wherein: